Vapor electric apparatus.



P. H. THOMAS.

VAPOR. ELECTRIC APPARATUS.

APPLICATION FILED OCT. 11. I913.

1,201,530. Patented 0ct.1' 7,1916.

CUR/m man/m OFFI PERCY H. THOMAS, OF UPPER MONTCI AIR, NEW JERSEY, ASSIGNOR TO COOPER HEWITT ELECTRIC CO., OF HOBOKEN, NEW JERSEY, A CORPORATION OF NEW JERSEY.

VAPOR ELECTRIC APPARATUS. i

Specification of Letters Patent.

Original application filed September 12, 1912, Serial No. 719,925. Divided and this application filed October 17, 1913. Serial No. 795,650.

To all whom it may concern Be it known that I, Pnnor H. THoMAs, a citizen of the United States, and resident of Upper Montclair, county of Essex, State of New Jersey, have invented certain new and useful Improvements in Vapor Electric Apparatus, of which the following is a specification.

My invention relates to the operation ofmercury vapor devices, more particularly when run under high pressure, in constant current circuits. Constant current circuits are utilized frequently and without difliculty in connection with consumption devices characterized by an absorption of voltage which increases only with rising current. When the serially operated device is, however, such that the voltage may rise without an increase in current, simple series operationhas the tendency to be unstable as will hereinafter be explained more particularly.

The object of the present invention is to secure a type of series circuit or designs of mercury vapor device such as can be successfully operated on a constant current circuit. The particular systems made use of will be explained more fully in connection with the several figures of the drawings, in which Figure 1 illustrates a constant current circuit feeding mercury vapor apparatus and Fig. 2 shows another such system adapted to alternating or direct current, and Figs. 3 and 4 show characteristic voltage-current curves.

In Fig. 4 I show a characteristic curve representing a device'having a voltage current relation which requires'no correction for series operation. It will be noted from this curve that an increase in voltage is obtainable only with an increase in current and that if the current be held steady the voltage will not exceed a certain amount. Fi 3, on the other hand, shows a characteristic voltage current curve which will be found to 3,: While the voltage is coming up duringthe warming process firom the lower voltage V to this point there is an increase in voltage whenever. there is an increase of current. But, a further increase in voltage w1ll occur in case of a continued rise of temperature on alternating current.

wlthout an increase in current and even with an actual decrease of current. This means in the case" of a serially operated mercury Patented Oct. 1'7, 1916.

absorbed in the vapor and hence the heat f produced therein increases so rapidly as to maintain all radiation losses and support. the actual vapor pressure with a lower current than would be suflicientto maintain the lower radiation losses at a somewhat lower temperature in the device and hence lower vapor pressure therein. When such lamps as those represented by the characteristic of Fig. 3 are operated in series on a constant current circuit trouble follows for if any one lamp is so constituted to' run a little hotter or happens for any reason to get a little hotter than the others its vapor pressure will immediately rise rapidly and since the current is maintained by the generator 1ts pressure and voltage goes up very rap-T idly until this device is injured or the ser1es of lamps is extinguished.

. Considering now Fig. 1, in which the individual mercury vapor devices 1, 1, 1, have a characteristic curve like that shown in Fig. 3, I show a method of constant current operation secured by the use of shunt circuits 2, 2, 2, which are automatically closed in shunt with the lamps 1. 1, 1, through the resistances, 3, 3, 3, 'by the thermostats, 4, 4, 4, or in one circuit by this thermostat whenever a lamp voltage tends to an excessive rise. The thermostat 4, when raised to a certain temperature by means of the elev-a-' tion of temperature of thelamp to which it is adjacent, will lower the part 6 until the contact 5 closes the shunt 2. The resistance 3 is so adjusted that the current then remaining in the lamp will drop slightly below the minimum danger current, thus permitting this lamp; to cool off. In some circuits these shunts would be thrown off and on more or less irregularly and thus preserve a perfect balance, on the average, between the lamps. i

In Fig. 2, I show a somewhat similar system, in which the lamp 7 is adapted for use Shunts are closed through the resistances, 8, 8, by way of the cut-outs, 9, 9, by the action of the magnets, 10, which are connected around the several lamps and thus measure the voltage thereon. The resistances, 11, 11, control the current in the magnets, 10, 10. The operation of this system is clear from that of Fig. 1, the chief difference being that in Fig. 2 the shunt circuit is closed by an electromagnet responsive to excess voltage on the lamp itself instead of by a thermostat. The currents through the resistances 8 are adjusted to abstract suflicient current from the lam to prevent its over-heating due to the fuIl current flow, while the resistance 11 is adapted to control the magnetizing current of the coil 10.

While I have shown some specific methods of gaining stability in these series circuits with containing devices having naturally straight upward characteristics, I do not wish to limit my invention to these particular features, for my invention is broader including the utilization of any specific means for correcting the tendency introduced by the use of constant current for individual devices to take abnormal operating temperatures or pressures. I do not wish to limit myself tomercury vapor apparatus, though my invention is especially adapted to this apparatus, nor do I wish to confine myself to a mercury electrode rather than one of some other appropriate material.

. Neither do I wish to limit myself to lamps operating in quartz tubes nor at the specific pressures here described. It is not necessary that the characteristic of such a lamp turn backward to the extent shown in the curve of Fig. 3; this figure, however, gives a good example of a device unstable on constant current.

This case is a division of my application Serial Number 719,925, filed September 12th, 1912.

I I claim as my invention:

1. A system of electrical distribution, comprising a constant current source and a series of electric translating devices each having a critical point beyond which the voltage of the device rises without limit with no rise in current, this critical point being for slightly difl'erent currents in lndividual devices, and means for securing stable operatlon of the lndividual devices comprismg a variable shunt to each device;

' 2. A system of electrical distribution comprlsing a constant current source and a series of translating devices each having .a critical point beyond which the voltage of the device rises without limit with no rise in current, this critical point being for slightly different currents in individual devices, and means for securing stable operation of individual devices comprising a variable shunt to each device, said shunt closing with an abnormal high temperature in said device.

3. A system of electrical distribution comprising a constant current source and a series of translating devices each having a critical point beyond which the voltage of the device rises without limit with no rise in current, this critical point being for slightly different currents in individual devices, and means for securing stable operation of the individual. devices comprising a variable shunt to each device, said shunt being controlled by a thermostat responsive to the temperature of the device.

4. In a system of electrical distribution in which devices each having a critical point beyond which the voltage of the device rises without limit with no rise in current, this critical point being for slightly different currents in individual devices are operated in constant current circuits, means for per- 5. A system of electrical distribution 1 comprising a constant current source and a series of translating devices each having a'critical point beyond which the voltage of the device rises without limit with no rise in current, this critical point being for slightly different currents in individual devices, means for securing stable operation of the individual devices comprising a variable shunt to each device, said means being resp'onsive to the voltage on the device.

Signed at New York in the county of New York and State of New York this 16th day of October A. D. 1913.

' PERCY H. THOMAS. Witnesses:

WM. H. CAPEL,. THos. H. BROWN. 

